Australian unionists Jacqui Park and Jane Worthington arrive home after being held in Sri Lanka

Two Australian unionists have arrived in Sydney after Sri Lankan authorities questioned them at length for attending a press freedom workshop.

Jacqui Park and Jane Worthington from the International Federation of Journalists went to a Free Media Movement in Colombo on Wednesday.

Officials from Sri Lanka's defence and immigration departments raided the meeting and demanded the Australian pair take them to their hotel and show the officials their passports.

Ms Park's husband Chris Warren says they were questioned for six hours on Wednesday.

"They thought they would then be allowed to leave but instead were cross-examined again for about nine hours on the Thursday," he said.

He says the questions were about the work they do with the federation, along with specific questions about what contact they have with Sri Lankan journalists who have fled the country and are living in exile in Europe or the US.

Mr Warren said authorities presented Ms Park with a dossier that was said to record her 17 past visits to Sri Lanka.

"It's clear that the Sri Lankan police have been keeping a detailed dossier on her movements in or out of the country over a long period of time which is, I think, disturbing."

Mr Warren said the case is designed to shut down criticism of Sri Lanka's human rights record ahead of the Commonwealth Heads of Government Meeting (CHOGM) this month.

Earlier on Friday, Foreign Minister Julie Bishop said she had raised the matter with her Sri Lankan counterpart at a meeting in Perth.